The invention relates to enclosed ink cups for pad-type printing machines.
On pad-type printing machines, an image engraved in a metal plate is provided with a thin film of ink by an ink cup that is slid over the surface of the plate. A doctor blade on the cup wipes the engraved surface as the ink cup is moved from the engraved area of the plate, leaving the ink at only the engraved image. A silicone pad then transfers the ink image from the plate to the object being printed. Typically the printing machines have used ink wells that are open to the atmosphere, and there have been recent environmental and health concerns related to vapors evaporating from the exposed ink.
In response to these concerns, enclosed ink cups have been proposed. For example, Phillip et al. U.S. Pat. No. 4,905,594 describes an enclosed ink cup that has a hollow body that can be bent in the area of its end face and employs a bellows structure to permit relative movement between the area of the end face and the remaining part of the hollow body in order to provide a sealable contact between the ink cup and the printing plate surface on printing plates whose surfaces exhibit deviations from a plane. Phlipp U.S. Pat. No. 4,557,195 describes an enclosed ink cup having a two-piece hollow body. The two parts are movable in relation to each other to ensure exact abutment on the printing plate surface independent of production tolerances.